My router ip was 192.168.1.1; I changed it to 192.168.1.107 at the router web interface. Now I know that was bad idea. How could I change it back as it was? I can't access web interface now
You may have to refresh your network connection on the client (release and renew its IP address) first.
If I knew the make and model of your router, I'd show you a specific picture of the back of your router... or a picture of the reset button. But, I can't get that specific. So, I'll be generic.
Image courtesy of TigerDirect.com
Now, not every router has a reset button that is so easy to access. Others have only a small hole that gives you access to it. Either way, examine your router, find the reset button, and push it for 10-15 seconds with the router plugged in. Then, treat it as if you just got it brand new. You can even follow the instructions in the manual for how to access it and set it up again. Chances are, if the default IP address for it was 192.168.1.1 and you had just used it before, it will once again be set to the same.